Coherent J/$\psi$ photo-production in Pb--Pb collisions with nuclear overlap, studied with ALICE at the LHC

L. Massacrier (1)

1 IPNO - Institut de Physique Nucléaire d'Orsay

The photoproduction of heavy vector mesons in the electromagnetic interactions of ultra-relativistic nuclei is thought to be sensitive to the gluon distributions in the nucleus and thus to cold nuclear effects like shadowing or gluon saturation. Besides the well known observations of vector meson production in ultra-peripheral collisions, first observations of an excess over the expected hadronic J/$\psi$ production at very low transverse momentum ($p_T < $0.3 GeV/$c$) in peripheral and semi-central nucleus-nucleus collisions both at LHC and RHIC energies were interpreted as the first sign of coherent J/$\psi$ photoproduction occurring in Pb-Pb collisions with nuclear overlap. The ALICE Collaboration published the J/$\psi$ coherent photoproduction cross sections in peripheral and semi-central Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV and forward rapidity ($2.5

Mots clés: CERN LHC Coll; coherence; overlap; rapidity; electromagnetic interaction; differential cross section: measured; nucleus nucleus; resolution; shadowing; gluon; experimental results; 2760 GeV-cms/nucleon; 5020 GeV-cms/nucleon; talk: Aix-Les-Bains 2018/10/01; heavy ion: scattering; lead; vector meson: photoproduction; transverse momentum: low; nuclear matter: effect; vector meson: heavy; parton: saturation; muon: pair production; J/psi(3100): photoproduction; nucleus; peripheral; ALICE

Domaines: Physique des Hautes Energies - Expérience [hep-ex]; Physique Nucléaire Expérimentale [nucl-ex]

L. Massacrier. Coherent J/$\psi$ photo-production in Pb--Pb collisions with nuclear overlap, studied with ALICE at the LHC. 9th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions, Oct 2018, Aix-Les-Bains, France. pp.181, ⟨10.22323/1.345.0181⟩. ⟨hal-02051536⟩